When I exposed my wafers the an alarm would sound the whole time the wafer was being exposed. The meter displayed what looked like the correct light intensity and after developing my wafers were exposed roughly as much as I would expect for the given exposure time.
Second thing
When aligning at high magnification there seems to be a problem with the focusing knobs or motors. The image in the display shifts by ~1/2 inch when adjusting the focus. The same is true when utilizing the top/bottom focus toggle. This image shift makes the grab image feature useless and makes alignment quite difficult. Hopefully there is some simple fix like tightening the optic mounts to eliminate the slack in the focusing
thanks
and good luck
nate